1. Field of the Invention
The invention relates to a method for making a heat sink for use with a CPU, and particularly to a heat sink having ultra-thin fins.
2. The Related Art
Heat sinks for use with CPUs in computer systems have recently become popular, and higher demands have been placed on the heat sinks due to increased signal transmission speed and capacity of the corresponding CPUs. Other than folded-fin type heat sinks as shown in U.S. Pat. Nos. 5,375,655 and 5,625,229, and implanted fin type heat sinks as shown in U.S. Pat. Nos. 5,038,858 and 5,509,465, traditional heat sinks are generally of the integral extrusion type as shown in U.S. Pat. Nos. 5,592,363 and 5,594,623 wherein the extrusion type can be further modified from a multiple-fin type, by additional milling, to a multiple-pin type as shown in U.S. Pat. No. 5,602,719. As speed of signal transmission of the CPU increases, so does the heat generated thereby. Therefore, it is necessary to increase the heat transfer efficiency of the heat sink. Heat transfer efficiency is commonly increased by reducing the thickness of the fins and increasing the density thereof, thereby increasing the total heat transfer surface area.
Unfortunately, due to manufacturing limitations, only a few manufacturers can fabricate an extrusion heat sink having fins with a thickness of 0.03" (i.e., minimum dimension). Even though the minimum thickness of fins of the heat sink can be obtained, a problem remains in mass production thereof. Extrusion is a method for making a continuous elongate part which is cut to a predetermined length. However, the 0.03" thickness of the fins is too fragile to endure the impact, vibration and force of the cutting process resulting in a high defect ratio and significantly increasing manufacturing costs. An EDM (electro-discharge machining) procedure has been introduced to gently cut the elongate parts to the desired length. However, such a procedure is time and cost inefficient.
Therefore, an object of the invention is to provide a time and cost efficient method for fabricating an ultra-thin fin heat sink.